How today's batteries work
To begin with, today's batteries are very modern and made of lithium known as Li-Ion, these batteries have mAh (milliamps per hour), there are several types of mAh variations, the higher this number the longer the battery life, but this will depend a lot on your use, the applications open in the background and many other things.
How long is the service life battery?
The useful life of new batteries is based on cycles, i.e. complete discharges. According to the companies, on average a Li-Ion battery lasts around 500 cycles, i.e. 500 complete discharges, after which the battery starts to lose its useful life and become bad, but this doesn't mean that it's addicted, but rather that its life has come to an end.
Waiting to fully discharge before charging?
Never wait until your phone is fully discharged before charging it. It's recommended to charge it when it's at about 20%, which will increase battery life a lot, but it's best to charge it when it's at 50%.
Many people say that you shouldn't charge your phone if it's on 90% or 80%, but that's just a lie, you can charge your phone whenever you need to, it's recommended.
Fiddling with your phone while it's charging and leaving it charging overnight
Many people have this question: can fiddling with your phone while it's charging reduce its battery performance? No, there's no such thing. The only thing that can happen is that it takes longer to charge, because the phone is being used constantly and using up its charge.
And leaving your cell phone charging overnight? You can do that too, because today's cell phones and chargers have a system that stops supplying power when the device reaches 100%, making it super safe, and it doesn't harm the battery's performance in any way.
Is your smartphone battery addictive or not?
No, your smartphone's battery doesn't die, what can happen is that you use too many apps and this ends up causing a bigger drain, sometimes you don't have any apps open and the battery runs out very quickly, but why? Applications running in the background is the answer, for this there is an application responsible for hibernating these applications to solve the problem, the Greenify which is available for download at the end of the post.
If your battery is still bad after that, it may have reached the end of its useful life, or it may be out of calibration, but an out of calibration battery changes almost nothing in terms of battery life, if you need to calibrate it you'll need to root it, below you'll find the apps to download.
Greenify
Calibrators
Video tutorial